carleton



Jan. 25, 1955 R. J. CARLETON, JR

ELECTRODE CLAMP FOR ELECTRIC FURNACES 2 Sheets-$heet 1 Filed Aug. 12. 1953 VENT 0R.

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2,700,692 ELECTRODE CLAMP FOR ELECTRIC FURNACES Richard J. Carleton, Jr., Chagrin Falls, Ohio, assignor to Republic Steel Corporation, Cleveland, Ohio, :1 corporation of New Jersey Application August 12, 1953, Serial No. 373,869 9 Claims. (Cl. 13' l6) This invention relates generally to an electric arc furnace, and more particularly to the electrode supporting and clamping structure for use in an arc furnace.

In electric arc melting furnaces used in the steel industry, the power is applied through three vertically disposed carbon electrodes projecting down through the roof of the furnace. The replaceable electrodes are slipped through generally circular collar supports and each elec- The collar support is at the end of an arm which extends over the furnace.

In these latter forms or Wedge from between the electrode and the collar. Such f new electrode holders and, 1n some cases, it was necessary to install an entirely new electrode holder and arm.

In the majority of electric arc furnaces, the electrodes are held in position by manually driving a wedge between the electrode and the holder. The expense of replacing the holders andfarms has retarded the adoption of the remotely controlled electrode holding devices referred to. Furthermore, the prior devices have not been entirely satisffactory in operation. They have been subject I to mechanical failure and because there was no means for reverting to manual clamping of the electrodes the envide an electrode clamp structure which may be operated mechanically from a remote location and may 'also be operated in an emergency by the usual manual operation.

Some devices have continned to use wedges which are mechanically or hy- V 8 Another important object of the invention is to provide 2,700,692 Patented Jan. 25, 1955 a clamping mechanism which can be readily installed on existing "equipment and requires only minor modification of 'such'equipm'ent.

'sion from heat, may become seized between the electrode and the clamping means. l The invention comprises an electrode clamping device clamping engagementwith the electrod as a wedge-backing block, in which case a wedge is disposed in slidabl'e engagement with the inner face of the block "between the block and the electrode. The cam means may be a-cylindrical member having one or more vention, showing the electrode holder, the arm for supporting the electrode holder and the mechanism for opcrating the electrode holder; a portion of the fluid-acmated.mechanism is indicated diagrammatically;

Fig. 2 is a side view of the apparatus as taken along the line 22 in Fig. 1;

Fig.) is a vertical section of the electrode holder taken along the line 3-3 in Fig. 1;

ig. 4 is a cross sectional view taken along the line 4-4 in Fig. '3;

Fig. 5 is a vertical sectional view taken along the line 5-5 in Fig. 3; and I Fig. 6 is a view of the rear face of a wedge adapted for use in the device,

s shown in Figs. 1 and 2, the electrode supporting app'aratusmcludes an electrode arm 10 which may be suit- Coolant such as water may be circulated through the cores in the contact portion and pipes 17, being fed to and returned therefrom through .pipes (not shown) carried in the electrode arm 10.

The coolant pipes 17 are connected to a wedge block 0 assembly indicated generally at 18. In the manual type of electrode supporting apparatus which is generally now in use, an electrode is positioned against the contact member 13 and a wedge is trode and the wedge block assembly to hold the electrode in position; the wedge being set and released manually by an operator standing on the roof of the furnace.

The apparatus embodying the invention is adaptedto be added to the usual type of existing apparatus with a milrtiimum of change to obtain a new and desirable resu The wedge block assembly 18 is made of greater lateral extent than in the usual manual type of electrode holder, and is formed of block support plates 21 (see Fig. 4) which are suitably attached to the coolant pipes 17 as by welding. The block support plates 21 are bolted through inner members 22 which form a cam block assembly having inner back-up block guide plates 23. Plates 23 form a guideway for wedge back-up block 25 which is adapted to move radially with respect to the axis of the electrode 15. A Wedge is disposed between electrode 15, to be held by the apparatus, and wedge back-up block 25. On the other side of the wedge back-up block is a cam member 26 which is rotatably mounted in the cam block assembly with its axis substantially parallel to the axis of the electrode to be held in the collar.

tary contact with the cam block assembly for rotation about the axis of said concentric portions. The cam member is also provided with cylindrical portions 27 of reduced diameter which are eccentrically disposed with 4 respect to the axis of the concentric portion 24 of the cam member. Push blocks 28 are provided with arcuate faces for enga ement with the reduced eccentric cylindrical portions 27 and are provided with planar faces for en agement with the rear side of the wedge back-up block 25.

The wed e back-up block 25 is formed of several components which include a front portion 30 and a rear portion 31, with an insulating plate 32 disposed between the members 30 and 31. Members 30 and 31 are fastened together by means of screws 33 which are also suitably insulated by insulated bushings 35. Washers 36 may be provided between the heads of the screws 33 and the insulated bushings. The insulation referred to may be electrical and thermal.

The wedge 20 has an arcuate face 37 adapted for engagement with the electrode 15, the arcuate face being adapted to contact the electrode over substantially the entire len th of the wedge as best shown in Fig. 3. As shown in Fi s. 3, 4 and 6, the rear face 38 of the wedge 20 is at a slight angle to the electrode engaging face 37 and is provided with a central fiat portion and two side flat portions 40 and intermediate rows of ratchet teeth 41, the teeth of which are staggered with respect to each other, as best shown in Fig. 6. Dog members 42 may be removably mounted at the upper end of the front portion 30 of the wedge back-up block. The dogs are held in position by screws 43 and are adapted to engage in the ratchet teeth 41 as best shown in Fig. 3.

The cam member 26 may be operatively connected to a fluid-actuated means including a cylinder 45, which is mounted adjacent the masthead 11. The cylinder is supported at its rear end by a bracket 46, which is provided with an car 47 adapted to be received between the arms of a clevis member 48 at the closed end of the cylinder 45. A pivot pin 50 is passed through drill holes provided in the clevis 48 and the ear 47. The other end of the cylinder is supported on a bracket 51, as shown in Figs. 1 and 2. Piston rod 52 of the cylinder is connected tothe cam by a tube arm 53, offset arm 55 and a cam lever 56. The cam lever 56 is provided with a square opening at one end in which is fixed the square upper end 57 of the cam 26. A retainer plate 60 which is connected to the cam by screw 59 maintains the cam lever in position on the cam. A pivot pin 61 connects the cam lever 56 to the. offset arm 55, the pin being passed through suitable drill holes provided in the members. The offset arm 55 may be connected to the tubular arm 53 by a threaded adjustable connector 62. As shown, the piston rod 52 may be connected to the tube arm 53 through a suitable insulator block assembly 63.

Cam lever 56 rotates the cam 26. as indicated in Fig. 1, by movement of the offset arm 55 and tube arm 53 in response to movement of the piston rod 52 in the cylinder 45. The cam, when rotated through the desired angle by movement of the cam lever 56, e. g., from the broken line position to the solid line position, applies its lift or The cam member may have concentric cylindrical portions 24 in sliding rohammered in between thelelecthrow action to the push blocks 28 against the wedge back-up block 25, including the front portion 30, displacing the wedge 20 in the direction of the electrode until the electrode is firmly clamped in its operating position. The mechanical advantage of the cam 26 and of the cam lever 56 is the medium through which the necessary clamping force is applied to the electrode 15.

The cylinder 45 has a piston 65 slidably mounted therein which is connected to the piston rod 52. As shown schematically in Fig. 1, the piston is moved by introducing fluid pressure into the cylinder on one side of the piston or the other by means of fluid lines 66 and 67 through which fluid may be directed in either direction. A suitable valve such as the valve 68 shown in Fig. 1 may be used to connect the fluid lines 66 and 67 selectively with the fluid pressure line 70 and the fluid exhaust line 71. The fluid may be liquid or gas. It has been found that air pressure provides a satisfactory means for operating the system.

In operation, the electrode 15 is clamped in position by compression of the adjustable wedge 20, wedge insulator block, i. e. the front portion 30 of the wedge back-up block 25, and the push blocks 28, by torque in the cam 26 and the cam lever 56. tension in the oifset arm 55 and in the tube arm 53 which is supplied by applying a regulated air pressure through the line 70 to the line 67 as shown in Fig. 1.

After clamping, the electrode may be held firmly in its operating position by applying a reduced regulated air pressure to the rod end of the air cylinder, i. e., through line 70, valve 68, and line 67. It may be noted that the electrode may also be held firmly in its operating position by adjusting the cam 26 and its operating mechanism so that the apex 72 of each of the cam portions 27 (see Fig. 4) is substantially in line with a line passing through the axis of the electrode 15 and the cam member 26 at the desired full clamping position. With this arrangement, it is not necessary to provide air pressure in the rod end, i. e. through the line 67 to the air cylinder. Fine adjustments in the length of the linkage between the cylinder 45 and the cam lever 56 may be effected by means of the threaded adiustable connector 62.

The electrode is released by exhausting air pressure through the line 67 and applying a regulated air pressure through the line 66 to the dead end of the cylinder. This change in air pressure compresses the tube arm 53, the offset arm 55 and reverses the direction of rotation of the cam lever 56 and of the cam 26, and causes the push blocks 28, the wedge back-up block 25 and its associated front portion 30 and the wedge to release their pressure on the electrode in order that it may be moved vertically for height adjustment or removal.

It will be appreciated that when the pressure on the electrode is released, the wedge 20 would have the tendency to slide down between the front portion wedge insulator block 30 and the electrode 15 and jam the electrode so that it could not be removed. The dogs 42 engage ratchet teeth 73 to prevent the wedge from sliding down when the pressure is released (see Fig. 3). As best shown in Fig. 5, one dog 42 is higher than the other to engage ratchet teeth 73 at difierent levels in the two rows 41 in the rear side of the wedge 20.

If it is desired for any reason, the apparatus of this invention can be operated by manual means. By loosening the screws 43 and turning the dogs 42 out of engagement with the teeth 73, the wedge 20 may be used in the usual manner, either driving it in by striking it on the upper portion 75 or removing it by placing a crowbar or other lever means in the ratchet teeth 73 and prying it upward, using the upper part of the wedge block assembly as a fulcrum. The staggering of the teeth 73 in the two rows assures that the end of the prying tool may be positioned under a tooth at the most advantageous level for prying the wedge upward.

The front portion 30 of the wedge block 28 is formed with a grooved guideway 76 with overhanging lips 77. The wedge is formed with shoulder portions 78 adapted to be loosely received in the grooved guideway defined in the front of the portion 30. By this arrangement, the wedge is maintained in operative position with the wedge block assembly during the remote mechanical operation of the apparatus. The wedge may also be operated manually, as indicated above, merely by removal of the dogs 42 from the teeth 73. The dogs may be removed by loosening the screws 43 and turning the dogs 42 out of engagement with the teeth 73. The wedge insulator block or front portion 30 of the wedge back-up block 25 is arranged for slidable movement in the guideway defined by the wedge guide blocks 80 fixed to the block support plates 21 by screws 81. Insulating plates 82 and bushing 83 may be provided to insulate the wedge blocks 80 from the block support plates 21.

A bottom plate 84 is attached to the bottom of the cam block assembly 22 by screws 79. The plate 84 serves to support the lower end of the cam 26 and provldes a lower support for the wedge back-up block 25, see Figs. 3 and 5.

A shield member 85, best shown in the lower part of Figs. 3 and 5, may be provided at the bottom of the wedge block assembly to shield the assembly to the bottom plate 84 of the block assembly by screws 86, with spacer members 87, disposed between the shield 85 and the bottom of the block assembly to permit air circulation under the block assembly.

Another shield member 19, Figs. 1 and 2, may be welded or otherwise suitably fixed to the masthead 11 below the cylinder 45 to protect the cylinder against heat and damage.

It will be understood that instead of connecting the contact member 13 to the wedge block assembly 18 by It will be appreciated from of the invention, that it operated by the usual manual operation.

It has been noted that the cylinder 45 is supported at its dead end by means of the bracket 46 and at its forward end by a bracket 51. A support bracket 88 may be disposed so as to support the offset arm 55 (see Figs. 1 and 2) from below.

It will be appreciated that the mechanism of this invention can be readily installed in existing equipment and requires little modification of the invention provides a clamping structure which has the invention provides a clamping device which includes the benefits of the wedge-setting form of clamping structure but eliminates the difliculty of removing the wedge which due to expansion from heat may become frozen between the electrode and the clamping means.

In accordance with the provisions of the patent statutes, I have herein described the principle of operation of the invention, together with the elements which I now consider the best embodiments thereof, but I desire Having thus described my invention, I claim:

1. In an electrode supporting structure an electrode clamping device comprising collar means in which an electrode may be clamped, a wedge block moveable with respect to said collar for clamping and releasing the electrode, means for moving said wedge block for clamping and releasing such electrode in the collar, a wedge moveable with respect to said block and means for releasably holding said wedge in substantially fixed relation to said wedge block.

2. In an electrode supporting structure an electrode clamping device comprising collar means in which the electrode may be clamped, a wedge block moveable radially with respect to said collar for clamping and releasing an electrode held in the collar, means for moving the wedge block radially, a wedge moveable axially with respect to said collar releasably held by said wedge block against said axial movement.

3. In an electrode supporting and clamping structure having an electrode arm for attachment to a masthead at one end, an electrode holding means at the other end, comprising a collar having a guideway extending radially with respect to the axis of said collar, means slidably mounted in said guideway for radial movement there along, cam means in engagement with the slidable means for moving said slidable means radially toward said collar, and means for operating the cam, including fluidactuated means disposed adjacent the masthead end of the arm and linkage means between said fluid-actuated means and the cam for operatively connecting the fluidactuated means to the cam.

4. The apparatus of claim 3 wherein the fluid-actuated means includes a cylinder pivotally attached at one end to the electrode supporting structure and havinga piston piston for movement of said piston,

the linkage means.

5. An electrode clamp comprising a clamping collar for holding an electrode having a guideway extending radially with respect to the axis of the collar, a wedge backing block slidably mounted in said guideway, a wedge loosely and releasably held by said wedge backing block, and a cam means in said guideway in engagement with the block for moving said block radially inward, and means for operating the cam for effecting such movement.

6. An electrode clamp collar comprising an arcuate face portion for engagement with the cylindrical surface of an electrode to be held in such collar, a wedge block assembly diametrically opposed to said arcuate face portion and means connecting the said block assembly and said arcuate face portion, said wedge block assembly comprising a guideway extending radially with respect to the axis of the collar, a wedge backing block member slidably mounted in said guideway for radial movement with respect to said collar, a wedge member loosely and releasably connected to the inner face of said wedge backing block member, and a cam means for engagement with the outer face of the wedge backing block member for moving said wedge backing block and wedge radially with respect to said collar, and means for actuating said cam means.

7. An electrode clamp collar for clamping an electrode, said collar having a guideway extending radially with respect to the center of the collar, a wedge backing block slidably mounted in the guideway for radial movement therealong, and having an inner and outer face with respect to the center of the collar, a wedge engaging the inner face of the wedge backing block and cam means in engagement with the outer face of the wedge backing block for moving said block and wedge radially, means for loosely holding the wedge against lateral displacement and releasable means for holding said wedge against vertical movement.

8. The apparatus of claim 7 wherein the means for loosely holding the wedge against lateral displacement comprises a guideway having overhanging lips formed on the inner face of the wedge backing block and cooperating shoulders formed on the wedge whereby the latter is slidably mounted in said guideway.

9. The apparatus of claim 7 wherein the means for releasably holding the wedge against vertical movement comprises teeth portions defined in the face of the wedge adjacent the wedge backing-block and removable dog members on the wedge backing block for releasably engaging in said teeth.

References Cited in the file of this patent UNITED STATES PATENTS 2,133,305 Payne Oct. 18, 1938 2,290,030 Brooke July 14, 1942 2,632,780 Whitehouse Mar. 24, 1953 

